OFFSET
0,2
FORMULA
a(n) = Sum_{k=1..n+1} A112500(n, k), n >= 0.
G.f: Sum_{n>=1} x^(n-1)/(Product_{k=1..n} (1 - k*x)^(n-k+1)). - Paul D. Hanna, Feb 16 2010
EXAMPLE
Contribution from Paul D. Hanna, Feb 16 2010: (Start)
G.f. A(x) = 1 + 2*x + 6*x^2 + 23*x^3 + 108*x^4 + 601*x^5 + ...
A(x) = 1/(1-x) + x/[(1-x)^2*(1-2x)] + x^2/[(1-x)^3*(1-2x)^2*(1-3x)] + ... (End)
PROG
(PARI) {a(n)=polcoeff(sum(m=1, 16, x^(m-1)/prod(k=1, m, (1-k*x +x*O(x^n))^(m-k+1))), n)} \\ Paul D. Hanna, Feb 16 2010
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Oct 14 2005
STATUS
approved